Sour

FYI, this is a bug in Mesen 0.9.5 specifically - it's fixed in the latest code, but there hasn't been any release with the fix yet.

The problem is essentially that the game detects that an Arkanoid controller is plugged in and ignores the standard controller input. If you set P2 to "Standard Controller" (USA version, set P5 to "None" for Japanese version) in the control options, the core should disconnect the arkanoid controller and the game should allow you to play with a regular controller.

The Arkanoid controller is meant to be used with the mouse, not a keyboard/gamepad. Move the mouse left/right to move, and click to select options or shoot the ball. If you're using a keyboard/gamepad, it makes more sense to just use the "standard controller" instead.

There is a /fullscreen command line option for Mesen that will open it in fullscreen (If you look at Help->Command line Options, you can get a list of all available options) Also, in Preferences->Shortcut Keys, you can map any keyboard/gamepad key to the "Exit" shortcut to use it to exit Mesen. Hope that helps